Genetic susceptibility to multiple sclerosis in a Shanghai Chinese population. The role of the HLA class II genes

The influence of the HLA-DRB1 and HLA-DQB1 allele heterogeneity on disease risk and severity in Iranian patients with multiple sclerosis

Multiple sclerosis (MS) is a common autoimmune disorder of the central nervous system. Recent studies have shown that the HLA-DRB1 and DQB1 alleles are associated with MS susceptibility and severity. However, this is controversial in different population studies. In the present study, the roles of HLA-DRB1 and DQB1 alleles and the amino acids were investigated on disease risk and severity in 120 Iranian patients with MS and 120 controls. Our findings indicate that the DRB1*1501 allele (OR = 3.203 P = 0.001), the DRB1*1501-DQB1*0602 haplotype (OR = 7.792 P = 0.003) and the DRB1*1501/0701- genotype (OR = 3.320 P = 0.006) and amino acid Leu26 (OR = 1.645 P = 0.005) and Phe9 (OR = 1.893 P = 0.009) on the DQβ1 chain are significantly associated with MS susceptibility. DRB1*1001 was the only allele that had a protective effect against MS (P = 0.0004). We also found that the DQB1*0303 allele was significantly associated with disease severity (mean Multiple Sclerosis Severity Score difference = 1.979, P = 0.002). However, protective effect of the DRB1*1001 against MS and also association of DQB1*0303 allele with MS severity need to be confirmed by larger sample size.

Relationship between HLA-DRB1 polymorphism and susceptibility or resistance to multiple sclerosis in Caucasians: a meta-analysis of non-family-based studies

OBJECTIVE

To identify the contribution of HLA-DRB1 alleles to susceptibility or resistance to multiple sclerosis (MS) in Caucasians through a meta-analysis of non-family-based studies.

METHODS

A systematic review of case-control studies in Caucasians was performed. Studies examining allele or phenotype frequencies were analyzed separately. Odds ratio (OR) and 95% confidence intervals (CIs) were used. We also used the relatively predispositional effect (RPE) method to analyze several allele frequency studies to avoid skewed results due to some strongly associated alleles.

RESULTS

A total of 5464 cases and 7809 controls from 14 allele frequency studies and a total of 5401 cases and 7538 controls from 23 phenotype frequency studies were analyzed. DRB1*15 was definitely the strongest risk factor for MS (allele group, Pc<0.00013, OR 2.59, 95%CI 2.34-2.87; phenotype group, Pc<0.00013, OR 3.35, 95%CI 2.95-3.80). DRB1*03 frequencies were significantly increased among MS cases in the phenotype group (Pc= 0.0013, OR 1.21, 95%CI 1.09-1.33) but not in the allele group. DRB1*14 and DRB1*07 showed protective effects against MS in both groups (DRB1*14, allele group, Pc<0.00013, OR 0.53, 95%CI 0.42-0.66; phenotype group, Pc<0.00013, OR 0.57, 95%CI 0.45-0.71; DRB1*07, allele group, Pc<0.0026, OR 0.75, 95%CI 0.64-0.87; phenotype group, Pc<0.00013, OR 0.67, 95%CI 0.61-0.73). By RPE method, DRB1*14, and DRB1*07 showed protective effects after excluding DRB1*15 from the analysis. DRB1*03 was significantly higher in MS cases than controls after removing both DRB1*15 and DRB1*14.

CONCLUSIONS

In Caucasians, we highlighted the definite protective role of HLA-DRB1*14 and DRB1*07 for MS. DRB1*03 is probably the only risk factor for MS besides DRB1*15 and a common genetic foundation for autoimmune disease. Targeting to these alleles may have potential values in prevention or therapy for MS in the specific population.

HLA-DR allele polymorphism and multiple sclerosis in Chinese populations: a meta-analysis

BACKGROUND

The association of human leukocyte antigen (HLA) genes and multiple sclerosis (MS) has been extensively investigated in Caucasians, but less so in Oriental races such as Chinese.

OBJECTIVES

To review studies on association of HLA class II alleles with MS in the Chinese population.

METHODS

An extensive search for published studies up to June 2010 was performed in the electronic databases. The meta-analysis facilities in the NCSS statistical package were utilized to analyze the findings in these studies. The odds ratios (ORs) of HLA-DR allele distributions in MS were analyzed against controls.

RESULTS

Eleven case-control studies were identified: nine genotyping and two serotyping studies. Six genotyping studies were suitable for HLA-DRB1 allele meta-analysis, which showed that HLA-DRB1*15 was associated with risk of MS in the combined group (308 cases and 407 controls; OR 1.39) while the HLA-DRB1*09 and HLA-DRB1*0901 alleles were protective. When the equivalent serotypes in these six studies were combined with the results from the two serotyping studies (431 cases and 652 controls) for a meta-analysis of HLA-DR serotypes, HLA-DR2 was a risk factor (OR 1.63) and HLA-DR9 was strongly protective in the combined group (OR 0.64).

CONCLUSIONS

Although limited data are available, our meta-analysis suggests that HLA-DR2/DRB1*15 are also associated with risk of MS in the Chinese population but less strongly so than in Western MS populations, whereas HLA-DR9 alleles appear to confer resistance in this population.

HLA-DPB1 0501 is associated with susceptibility to anti-aquaporin-4 antibodies positive neuromyelitis optica in southern Han Chinese

OBJECTIVES

To analyze the role of HLA-DRB1 and -DPB1 alleles in the pathogenesis of neuromyelitis optica (NMO) and multiple sclerosis in Southern Han Chinese.

METHODS

Thirty serum anti-aquaporin 4 antibodies (AQP4-Ab)-positive NMO patients, 53 conventional multiple sclerosis (C-MS) patients, and 93 controls (CTLs) were enrolled. The HLA-DRB1 and -DPB1 alleles of the subjects were determined by sequencing-based typing (SBT).

RESULTS

The frequency of the DRB1 0901 was lower in NMO patients than in CTLs (P(uncorr)=0.022, OR: 0.194, 95% CI: 0.043-0.876), and DRB1 1602 was higher in NMO patients than in C-MS (P(uncorr)=0.038, OR: 3.491, 95% CI: 1.024-11.896) and CTLs (P(uncorr)=0.051, OR: 2.711, 95% CI: 0.971-7.556). The frequency of DPB1 0501 was significant higher in NMO patients than in C-MS (P(uncorr)=0.018, OR: 4.629, 95% CI: 1.235-17.350) and CTLs (P(uncorr)=0.001, P(corr)=0.022, OR: 7.096, 95% CI: 2.011-25.044).

CONCLUSIONS

DPB1 0501 correlates with risk of AQP4-Ab positive NMO in Southern Han Chinese.

Association of susceptibility to multiple sclerosis in Southern Han Chinese with HLA-DRB1, -DPB1 alleles and DRB1-DPB1 haplotypes: distinct from other populations

Association of HLA class II with multiple sclerosis (MS) has been widely studied in both Western and Oriental populations. However, such an association is not well documented in Chinese. The objective of this study was to examine the association between the susceptibility to conventional MS in Southern Chinese with HLA-DRB1,-DPB1 alleles and putative DRB1-DPB1 haplotypes. Genotyping of HLA-DRB1 and -DPB1 alleles was performed in 60 patients with conventional MS and 95 controls. Allele frequencies were compared between patients and controls to identify MSassociated alleles. Relative predisposing effect method was used to compare haplotype frequencies in patients and controls and to identify possible predisposing DRB1-DPB1 haplotypes, which were further examined for differences in haplotype carriage rates between the two groups. We found that the allele frequency of DRB1*1501 was not different between patients (18.3%) and controls (21.1%) ( p = 0.837). In contrast, frequency of the DPB1*0501 allele was significantly higher in patients (90%) than in controls (67.4%) (odds ratio = 4.36, p = 0.0013, pcorr = 0.025). DRB1-DPB1 linkage haplotype in patients (8.33%) was significantly higher than in controls (0%) ( p < 0.0001) and the carriage rate of this haplotype was significantly increased in patients (15%) as compared with controls (0%) ( p = 0.00013, pcorr = 0.003). Combined, these results suggest that HLA-DRB1*1501 is not associated with susceptibility to conventional MS in Southern Chinese. Instead, both the DPB1*0501 allele and the DRB1*1602- DPB1*0501 haplotype are strong predisposing factors for conventional MS in this population. Our results establish that the HLA profiles of MS in Southern Chinese are distinct from other populations.

Analysis of HLA DR2&DQ6 (DRB1*1501, DQA1*0102, DQB1*0602) haplotypes in Iranian patients with multiple sclerosis

Multiple sclerosis (MS) is prototype of inflammatory demyelinating disease of the central nervous system .The etiology of MS remains unclear, but according to current data the disease develops in genetically susceptible individuals and may require additional environmental triggers. The human leukocyte antigen (HLA) class II alleles (DRB1*1501, DQA1*0102, DQB1*0602) may have the strongest genetic effect in MS. In this study, the role of these alleles were investigated in 183 Iranian patients with multiple sclerosis and compared with 100 healthy individuals. HLA typing for DRB1*1501, DQA1*0102, DQB1*0602 was performed by polymerase chain reaction (PCR) amplification with sequence-specific primers (PCR-SSP) method. The results show that, HLA DR B1*1501 was significantly more frequent among MS patients (46% vs. 20%, PV = 0.0006) but DQA1*0102 haplotype was negatively associated with MS (30% vs. 50%, PV = 0.0049) and no significant association was found with DQB1*0602 and MS patients in comparison with control group (24% and 30%, PV = 0.43). No significant correlation was observed among these alleles with sex, type of disease; initial symptoms, expanded disability status scale (EDSS), as well as age at onset and familial MS. This study therefore indicates that there is no association of above HLA haplotypes with clinical presentation, disease duration, and disability in Iranian patients with MS which is in line with other previous studies in different ethnic groups.

HLA-DR15 haplotype and multiple sclerosis: a HuGE review

An association between multiple sclerosis (MS) and the human leukocyte antigen (HLA) complex, a dense cluster of genes on the short arm of chromosome 6, was first noted over 30 years ago. In Caucasian populations of Northern European descent, the DR15 haplotype (DRB1*1501-DQA1*0102-DQB1*0602) has been hypothesized to be the primary HLA genetic susceptibility factor for MS. However, studies of other populations have produced varying results. Thus, the authors reviewed the literature for articles on the association between the DR15 haplotype and MS. They identified 72 papers meeting the inclusion criteria: human genetic studies written in English that were published between 1993 and 2004 and that reported allele frequencies for HLA-DRB1*1501, HLA-DQA1*0102, or HLA-DQB1*0602 or the frequency of the DRB1*1501-DQA1*0102-DQB1*0602 haplotype. Most of the studies identified used a case-control design (n = 60), while the remainder used a family-based design (n = 22). In most of these papers, investigators reported a higher frequency of the DR15 haplotype and/or its component alleles among MS cases than among controls. However, the authors' confidence in these results is tempered by factors related to study design that may have biased the outcomes.

Evidence for novel DRB1*15 allele association among clinically definite multiple sclerosis patients from Mumbai, India

Multiple sclerosis (MS) is a clinically heterogeneous demylinating disease and an important cause of acquired neurologic disability. MS has been reported from different regions of India and its infrequency has been attributed to have genetic implications. Further, a high incidence of MS and its human leukocyte antigen B12 (HLA-B12) associations have been reported among highly inbred Parsi population from Mumbai. However, consistent HLA associations have not been reported from India. We analyzed the HLA-B, -Cw, and -DRB1 allele associations among 23 clinically definite Western Indian non-Parsi MS patients and compared them with 146 ethnically matched clinically normal individuals. HLA serologic (A, B, and Cw) as well as molecular (DRB1) typing methodology was followed. The study revealed a significant increase of HLA-A11 (24% vs. 13%; OR = 2.6; EF = 0.14; 95%CI = 1.1-3.05), B16 (4.3% vs 0.3%; OR = 13.8; EF = 0.03; 95% CI = 1.19-134.44), Cw7 (15.2% vs 3.7%; OR = 5.46; EF = 0.12; 95% CI = 0.944-17.86), and DRB1*15 (21.7% vs 2.2%; OR = 16.15; EF = 0.19; 95% CI = 1.33-68.64). Further molecular subtyping of HLA-DRB1*15 among the patients revealed two novel alleles, DRB1*1506 (20%) and DRB1*1508 (30%), along with the commonly reported DRB1*1501 (50%) for the first time in MS patients that were hitherto unidentified from other parts of India and world as well. This study reveals that there is a complexity of the genetic susceptibility to MS in different populations studied and reported.

Multiple sclerosis in the Japanese population

Multiple sclerosis (MS) in Asian populations is characterised by the selective and severe involvement of the optic nerve and spinal cord as well as low prevalence rates. 15-40% of cases of MS in Japan are of this "opticospinal" type. This form of MS generally has a higher age at onset and a higher female to male ratio than conventional MS. Opticospinal MS is also characterised by frequent relapses, severe disability, few brain lesions visible on MRI, long lesions extending over many vertebral segments visible on spinal-cord MRI, pleocytosis and an absence of oligoclonal bands in the CSF, and a pronounced shift in the responses of T-helper-1 and T-cytotoxic-1 cells throughout relapse and remission phases. Conventional MS in Japanese people is, like MS in white people, associated with HLA-DRB1*1501, whereas opticospinal MS is associated with HLA-DPB1*0501. In Japanese people born after modernisation in the 1960s, the ratio of conventional to opticospinal MS has increased rapidly. Opticospinal MS is likely to have a distinct immune-mediated mechanism, which is not operative in conventional MS.

Genetics of multiple sclerosis: linkage and association studies

Multiple sclerosis (MS) is a demyelinating autoimmune disease of the central nervous system caused by an interplay of environmental and genetic factors. The only genetic region that has been clearly demonstrated by linkage and association studies to contribute to MS genetic susceptibility is the human leukocyte antigen (HLA) system. The majority of HLA population studies in MS have focused on Caucasians of Northern European descent, where the predisposition to disease has been consistently associated with the class II DRB1*1501-DQA1*0102-DQB1*0602 haplotype. A positive association with DR4 was detected in Sardinians and in other Mediterranean populations. Moreover DR1, DR7, DR11 have been found to be protective in several populations. Systematic searches aimed at identifying non-HLA susceptibility genes were undertaken in several populations by means of linkage studies with microsatellite markers distributed across the whole genome. The conclusion of these studies was that there is no major MS locus, and genetic susceptibility to the disease is most likely explained by the presence of different genes each conferring a small contribution to the overall familial aggregation. The involvement of several candidate genes was tested by association studies, utilizing either a population-based (case control) or a family-based (transmission disequilibrium test) approach. Candidate genes were selected mainly on the basis of their involvement in the autoimmune pathogenesis and include immunorelevant molecules such as cytokines, cytokine receptors, immunoglobulin, T cell receptor subunits and myelin antigens. With the notable exception of HLA, association studies met only modest success. This failure may result from the small size of the tested samples and the small number of markers considered for each gene. New tools for large scale screening are needed to identify genetic determinants with a low phenotypic effect. Large collaborative studies are planned to screen several thousands of patients with MS with several thousands of genetic markers. The tests are increasingly based on the DNA pooling procedure.

Additive effect of the HLA-DR15 haplotype on susceptibility to multiple sclerosis

Multiple sclerosis (MS) has been associated with the human leukocyte antigen DR15 allele in Caucasians of North and Central European origin. However, the relative effect of the DR15 homozygous and the DR15 heterozygous genotypes on the disease susceptibility is unclear. Based upon results from three North European studies we have examined this by meta-analysis. Our results suggested that the effect of the DRB1*1501,DQA1*0102,DQB1*0602 haplotype on the susceptibility to MS is additive, perhaps reflecting that development of the disease is facilitated by a high density surface expression of the antigen presenting molecules encoded by this haplotype. Possible implications of our finding to future studies of the genetic background of MS is discussed.

Genetic susceptibility to multiple sclerosis: detection of polymorphic nucleotides and an intron in the 3' untranslated region of the major histocompatibility complex class II transactivator gene

The master player in the transcriptional regulation of major histocompatibility (MHC) class II genes is a factor known as the MHC class II transactivator (CIITA). In this study we searched for polymorphisms in the 5' and 3' ends of the human CIITA gene to assess whether or not there is an association between alleles of this gene and multiple sclerosis (MS). Polymorphism screening based upon detection of single strand conformational changes (SSCP analysis) followed by sequencing revealed six single nucleotide variations, namely one in the promoter utilized by B cells and five in the 3' untranslated region (UTR) of the gene. Determination of alleles at these polymorphic sites was facilitated by treatment of amplified DNA fragments with a panel of appropriate restriction enzymes. The distributions of CIITA alleles did not differ between MS patients and control subjects (p > 0.05). After subgrouping of the patients into relapsing-remitting MS and primary progressive MS we found that the distribution of promoter alleles in the latter of these two patient groups differed from that of healthy control subjects (p = 0.04). There was no evidence of linkage disequilibrium between the polymorphic site in the B cell specific promoter and those in the 3' UTR. Based upon the polymorphic sites in the 3' UTR we identified two common CIITA haplotypes which were present at similar frequencies in patients and control subjects. Assuming that susceptibility to MS depends upon type of MHC class II molecule as well as the amounts of expressed class II molecules we tested for interaction between DR15 status and CIITA alleles. No such interaction was detected. Unexpectedly, we identified an intron in the 3' UTR of the human as well as the mouse CIITA gene. Due to the proximity of these introns to the termination codon in both the human and mouse CIITA gene, the mechanism for regulation of transcript stability known as nonsense-mediated decay is probably not involved in the posttranscriptional control of the expression of these genes. So far, the function and significance of the intron in the human and mouse CIITA genes are unknown.

CTLA4 in multiple sclerosis. Lack of genetic association in a European Caucasian population but evidence of interaction with HLA-DR2 among Shanghai Chinese

In the present study we searched for an association between multiple sclerosis (MS) and the gene encoding the cytotoxic T lymphocyte antigen 4 (CTLA4). Our experimental approach involved amplification of DNA fragments of the promoter and exon 1 of this gene containing single nucleotide polymorphisms followed by treatment of the amplified fragments with restriction enzymes for allele determination. Included in the study were 84 MS patients and 125 healthy control subjects from a population of white Caucasians. We also examined 42 MS patients and 86 healthy control subjects of Shanghai Chinese origin. Significant differences in the distribution of genotypes or haplotypes of the CTLA4 gene were not observed between MS patients and control subjects in either of the two populations (P>0.05). Moreover, we were not able to confirm a previous finding of an association between relapsing-remitting MS and the heterozygous genotype A/G of CTLA4 exon 1. There was no evidence to suggest that interaction between HLA-DR2 and CTLA4 is involved in the development of MS among European Caucasians (P>0.05). Opposed to this, analysis of the Shanghai Chinese suggested presence of such interaction (P=0.02). Our results do not support the assumption that CTLA4 influences susceptibility to MS in European Caucasians. On the other hand, they raise the possibility that the development of MS in other ethnic groups involves interaction between CTLA4 and DR2.

Genetic risk and protective factors for idiopathic inflammatory myopathy in Koreans and American whites: a tale of two loci

OBJECTIVE

To better understand genetic contributions to autoimmunity, immunogenetic markers were studied in two racially discrete and geographically isolated populations of patients with idiopathic inflammatory myopathy (IIM).

METHODS

Clinical characteristics, as well as clinical and autoantibody subsets, were defined in 151 American white patients and 50 Korean patients with IIM. HLA-DRB1 and DQA1 genotyping was performed on patients and racially matched controls by standard molecular techniques. Gm allotypes and phenotypes were determined by the hemagglutination-inhibition method.

RESULTS

HLA-DRB1*0301, the linked allele DQA1*0501, and DRB1 alleles sharing the first hypervariable region motif 9EYSTS13 were major genetic risk factors for the development of myositis in whites (corrected P [Pcorr] < 0.0004, odds ratio [OR] 11.2, 4.5, and 3.1, respectively, for each factor versus controls). Although both the white and Korean patients had a similar distribution of clinical characteristics, autoantibody profiles, and clinical groups, no HLA-DRB1 nor DQA1 allele or motif was found to be a risk factor for IIM in the Korean patients. However, DRB1*14 was a protective factor in Korean patients without myositis-specific autoantibodies (Pcorr = 0.004, OR 0.046). In addition, although no Gm phenotype or allotype was identified as a risk factor in whites, Gm 21 was a protective factor for the development of IIM in Koreans (Pcorr = 0.024, OR 0.3).

CONCLUSION

Although myositis patients in the US and Korea share similar clinical and serologic features, the immune response genes predisposing to and protecting from myositis in each of these ethnic groups differ at two chromosomal loci. These data suggest that multiple genetic loci should be studied to identify risk and protective factors for some autoimmune diseases in various ethnic populations.